24 Hours In Police Custody viewers will witness one of the series' most gruesome investigations ever in tonight's show.

“A Second Chance” follows the case of Mark Cutmore, who was given another opportunity after being involved in an attempted GBH case.

At the time, having been visibly remorseful over his actions, the judge released him, crediting him for acknowledging his wrong doing.

Two years later in April 2017, Cutmore is arrested on suspicion of attempted murder after hitting his then partner on the head with a kettle before attempting to strangle her and stabbing her with a pair of scissors.

Cutmore will not admit to deliberately hurting Michelle and without her corroboration, the charges of attempted murder are reduced.

Cutmore (pictured) being checked into the police station in 2015 after being arrested for attempted GBH (Image: Channel 4)

Cutmore (pictured) in 2017 after being arrested on suspicion of murder (Image: Channel 4)

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DC Jeremy Atkins (pictured) thinks it's impossible to be sympathetic to someone after they have lied (Image: Channel 4)

Cutmore is adamant he left the flat before Michelle but CCTV footage shows her coming out of the flat prior to him leaving the builidng.

DC Jeremy Atkins says: "I think it’s impossible to be sympathetic to someone after they’ve lied to you. Just cause someone’s crying doesn’t make them genuine and believable. Everyone can put on a sob story if they want too."

Cutmore still claims he was defending himself but without victim support the charge is dropped to GBH with intent.

Michelle says: "It was terrifying, horrible. I couldn’t close my eyes for a bit after, just the thought, it just, his eyes. He was spitting anger, like frothing at the mouth, he was like really, really angry.

"But you know it’s like, he loves me, and I know he didn’t mean to do that and it was the spice that did that to him that night and I can remember thinking, ‘don’t get police involved, don’t get police…,'cause I didn’t want him to get him into trouble because he didn’t mean it, you know he didn’t mean…I could tell, he didn’t mean it."

Cutmore (pictured in 2015) wrote a letter to the 24 Hours in Police Custody producers (Image: Channel 4)

Cutmore pleaded guilty to causing grievous bodily harm (GBH) with intent and was sentenced at Luton Crown Court on 16 June 2017.

DCI Jeremy Atkins, from the Bedfordshire Police Emerald team, said: “It is difficult to comprehend how someone can carry out such a horrific and brutal assault on anyone, let alone their own partner.

"Despite suffering serious injuries, the victim has fortunately made a good recovery, but attacks like this can leave mental scars as well as physical."

In a surprising turn nine months into his sentence he writes a letter to the 24 Hours producers.

In the letter, he writes: "I’m truly sorry to everyone I’ve affected by committing this nasty crime. I was drunk on tablets and spice.

"It doesn’t excuse my actions but it does explain them, all I’m going to do in the future is be a great role model to my children, which will involve no drink and no drugs ever again."